Hydrodamalis gigas 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Sirenia Dugongidae

Scientific Name: Hydrodamalis gigas
Species Authority: (Zimmermann, 1780)
Common Name(s):
English Steller's Sea Cow

Assessment Information [top]

Red List Category & Criteria: Extinct ver 3.1
Year Published: 2016
Date Assessed: 2016-04-04
Assessor(s): Domning, D.
Reviewer(s): Morales-Vela, B.
The last population of Steller's Sea Cow was discovered by a Russian expedition wrecked on Bering Island in 1741. The genus is thought to have become extinct by 1768.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Steller's Sea Cow was known from the Bering Sea. The last population was discovered by a Russian expedition wrecked on Bering Island in 1741. It is likely that a population also persisted in at least the western Aleutian Islands into the 18th century (Domning et al. 2007). There is also evidence of a population at St. Lawrence Island in the northern Bering Sea more than a thousand years ago (Crerar et al. 2014).

A catalogue of osteological specimens of H. gigas in the world’s museums, with a history of their collection, was published by Mattioli and Domning (2006). In the Pliocene and Pleistocene, Hydrodamalis occurred from Japan to Baja California, Mexico (Domning 1978, Domning and Furusawa 1995), a range that coincided with that of the Sea Otter Enhydra lutris.
Countries occurrence:
Regionally extinct:
Russian Federation; United States
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Steller's Sea Cow was discovered in 1741 in the shallow waters around the uninhabited Commander Islands. The relict Bering Island population was studied by Georg Steller (a naturalist and physician onboard Vitus Bering's ship wrecked on the island in 1741). The sea cow was an easily available source of meat and the islands became a regular stop-over and stocking up point for Russian fur hunters until 1762-1763. Ruthlessly hunted, Steller's Sea Cow was probably extinct by 1768. Turvey and Risley (2006) presented a preliminary mathematical model of its extinction dynamics, providing evidence that the initial Bering Island sea cow population must have been higher than the 1,500 animals suggested by Stejneger (1887) to allow the species to survive even until 1768. Estes et al. (2015) presented further population modelling to show that hunting of sea otters could have driven the sea cows to extinction even without direct human overkill of the latter.

Additional data:

Habitat and Ecology [top]

Habitat and Ecology:When discovered, Steller's Sea Cow inhabited the shallow cold waters around the Commander Islands in the Bering Sea, grazing on kelps.

Threats [top]

Major Threat(s): Hydrodamalis was slaughtered for its meat and leather. Anderson (1995) discussed the ecological interaction between sea cows, sea otters, Strongylocentrotus sea urchins, and kelp, and suggested that human predation on sea otters (resulting in a nearshore community dominated by sea urchins, which largely eliminate shallow-water kelps leading to their replacement by chemically defended deep-water species) was a major factor, along with hunting, in sea cow extinction. Turvey et al. (2006) assessed whether hunting alone would have been sufficient to wipe out the sea cow, and showed that the speed of sea cow disappearance on Bering Island indicates that hunting alone was more than sufficient to exterminate the species without having to invoke any additional ecological pressures. Conversely, Estes et al. (2015) argued that hunting of sea otters alone could account for the sea cows’ extinction. Since both pressures actually occurred, there is no difficulty in understanding the rapid disappearance of Hydrodamalis from the Commander Islands.

Conservation Actions [top]

Conservation Actions:

This species is now extinct. However, bones of other marine mammals may be misrepresented and trafficked as "Steller's Sea Cow" or "mermaid ivory", thereby circumventing CITES and other legal restrictions (Crerar et al. 2016).

Citation: Domning, D. 2016. Hydrodamalis gigas. The IUCN Red List of Threatened Species 2016: e.T10303A43792683. . Downloaded on 22 January 2017.
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